St. V Padilla, head teacher at the ABCD Head Start daycare at Bassick High School, comforts Maneldaliz Mejia, 4, as she waits to be picked up following a bomb threat evacuation of the school in Bridgeport, Conn. on Wednesday, May 1, 2013. Daycare children were evacuated down Fairfield Avenue from the school to the front steps of the Klein Memorial Auditorium.

BRIDGEPORT -- Authorities evacuated Bassick High School and scoured the building with bomb-sniffing dogs Wednesday morning after a student scrawled bomb threats on the building's walls.

Superintendent of Schools Paul Vallas confirmed late Wednesday that authorities had identified a student believed to be responsible for the threats through footage on security cameras. Vallas declined to identify the student and it was not clear what, if any, charges would be filed against him.

The police search Wednesday morning did not discover any explosives, city police spokesman William Kaempffer said, characterizing the effort as "an excess of caution."

"Anything of this nature we treat as credible until we learn differently. We're always going to err on the side of caution and thankfully this incident proved unfounded," he said of the threats, which were written directly onto the building's walls.

Bassick was set to return to normal Thursday morning, though the discovery of the threats on Wednesday cut the school day short about 10:30 a.m. and brought a tension to the Clinton Avenue campus.

After the discovery of the threats, which claimed multiple bombs would detonate at a specific time that city police did not disclose, the State Police bomb squad and a dog trained to sniff out explosives, along with its handler, searched the sprawling school, at one point focusing on the attached Business Academy building.

An AMR ambulance pulled into the school parking lot about 12:30 p.m., joining several marked and unmarked Bridgeport police vehicles.

School officials said in a statement at 12:50 p.m. that the building was secured and no threat was found.

"All students and staff are safe at this time and the Bridgeport police department has informed us the threat has been resolved and the building is clear for school to be back in session tomorrow morning," the statement said.

Kaempffer said the school was evacuated and students sent home for the day "in an excess of caution. But we thoroughly investigate any and all reports of this type."

Children in an ABCD day care inside the school were ordered to go to the nearby Klein Memorial Auditorium. Several students waited on the outside on the steps with their teacher, St. V. Padilla.

"Nobody told us what was going on, just to take the kids over to the Klein," he said. "We called their parents and most of them were picked up right away."

Many Bassick High students walked home or enjoyed the spring day outdoors, melting away within minutes of the school's closing.

Wednesday's evacuation and bomb threat was the second time this week police were sent to the school.

On Tuesday, a teenager was arrested after police said he brought a realistic toy machine gun to school. Gael Tshimbalanga Kalonda, 18, of Highland Avenue, was charged with second-degree breach of peace.

Kalonda came in the front door at Bassick High School and was walking through the metal detector when an object was detected in his book bag, police said. Police searched the bag and found the toy gun. They said the orange tip of the gun and its trigger had both been painted black in order to make it look more like a real weapon.